1. Field of the Invention
The invention refers to a process for controlling the movement of a universally swivellable cutting arm of a partial cut cutting machine comprising a first hydraulic drive means for lifting and lowering the cutting arm and a further hydraulic drive means for swivelling the cutting arm transversally relative to the direction of lifting movement and lowering movement, as well as to an apparatus for performing this process.
2. Description of the Prior Art
Partial cut cutting machines equipped with a universally swivellable cutting arm comprise in most cases hydraulic cylinder-piston-aggregates for lifting and lowering the cutting arm in essential vertical direction as well as a swivel drive, which may, for example, be effected by a hydraulically actuated tooth rack meshing with the toothed wheel of a traversing gear. Swivelling of the cutting arm is, as a rule, effected around an axis extending substantially normal to the plane of the chassis, noting that there are swivelled together with the traversing gear around this substantially vertical axis also the hydraulic cylinder-piston-aggregates provided for lifting and lowering the cutting arm. The cutting arm can thus be lifted or lowered in any horizontally swivelled position.
When cutting profiles by means of partial cut cutting machines having arranged on the free end of the cutting arm cutting heads rotatably supported for rotation in transverse relation to the longitudinal axis of the cutting arm, the advancing direction is most frequently selected in direction of the axis of the rotational movement of the cutting heads. After having attained the nominal profile, the cutting arm is lifted or lowered for the so-called preselected depth of cut, whereupon advancing movement is performed in the opposite direction and again in substantial horizontal direction. It is on account of the construction of such cutting machines that there remains centrally between both cutting heads arranged on the free end of the cutting arm a rib when lifting or lowering the cutting arm for achieving the new preselected depth of cut. In the following, this rib must be broken away when swivelling the cutting arm in a substantially horizontal direction. In dependence on the nature of the rock and on the construction of the machine, this rib may be too big for being broken away without special measures by merely swivelling the cutting arm. In these cases, swivelling of the cutting arm in the assumed new position is not easily possible and expensive manual control operations are required for breaking away this rib to be in the position to continue cutting work in the opposite direction.